Piston-packing.



G. CHRISTBNSON.

PISTON PACKING.

APPLlGATION FILED 110 1.22, 1911. 1,076,269. Patented 0ct.21,1913.

2 SHEETSSHEET 1.

G. GHRISTENSON.

PISTON PACKING.

APPLICATION FILED Nov. 22, 1911 1,076,269. Patented 0ctr21, 1913.

2 SHEETS-SHEET Z.

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GEORGE onms'rninson, or JAMAICA, NEW Yomz', Assionoa 'ro H. w. JOHNS- H-ANVILLE GGMPANY, A

eoiaronazrron or new rosin PISTON-PACKING.

Specification of Letters Patent.

Patented Oct. 21, 1913.

Application filed November 22, $311. Serial fie. assess.

To all whom it may concern Be it known that I, GEORGE CHms'rENsoN, a citizen of the United States of America, residing at Jamaica, New York city, county of Queens, State of New York, have invented certain new and useful Improvementsin Piston-Packing, of which the following is a specification.

My invention relates to piston packing and is specifically designed to produce an improved form of air tight piston packing for use in air brake structures.

My present invention is an improvement on that shown in my Patent No. 862,5t0, dated August 6, 1907. The construction shown in my aforesaid patent, while sulib ciently efiicient for certain sizes of eylin ders encounters certain disadvantages when the attempt is made to apply it to pistons of large diameter in that the packing expander ring being formed of metal of uneven thickness, it is practically'difiicult to form a sufiicjiently large ring out ethighly tempered for all sizes.

spring metal by the usual processes of drawing or the like. Furthermore, it is the general opinion of those skilled in the air brake art that when large pistons are employed on cylinders which are usually placed horizontally under the cars, there is a tendency for the weight of the piston to produce eX- cessive wear on the packing at the lower side of the piston. My present invention overcomes these difficulties among others and produces a highly etlicient piston paclv ing which can be made with equal ease for any size of piston and is equally eliicient The best form of apparatus embodying my invention at present known to me is illustrated in the accompanying two sheets of drawings in which,

Figure 1 is an axial section of a cylinder and piston with parts broken away. Fig. 2 is a detail edge view of the piston follower shown in Fig. l. Fig. 3 is a plan View of the follower shown in Fig. 2. Fig. 4 is a detail perspective View of the piston packing expander ring used in my present invention,'and Fig. 5 is a, cross section of a mod1- fied form of piston follower.

Throughout the drawings like reference characters indicate like parts.

1 indicates the cylinder and 2 the ordi Qnary piston head.

3 is the radial flange and 4 the upturned flange of ordinary cup shaped packing of leather or similar material.

is a packing expander ring of elastic material, usually spring steel, which is formed of a strip of material of a proximately even thickness throughout, ent or otherwise shaped so as to have the upturned flange 6 and the radially projecting flange 7.

8 is a piston follower of specialform. This follower is usually formed of cast metal and it and the piston head are so shaped that when assembled and held together by the bolts 15, 15, or other convenrent means there is a circumferential recess 9 left between the piston and the follower in which both the cup shaped packing and the expander ring 5 cumferential recess is usually formed b making the outer flange 18 of the piston to lower of an external diameter equal to the external diameter of the piston head 2, so that both will it snugly into the cylinder 1. The inner flange or ring 17 of the piston follower is also provided on its under face with an annular recess 10 in which the radial flange 7 of the expander ring can he loosely seated when the parts are assembled, as

shown in Fig. 1, and the follower forced down upon the radial flange 3 of the cup packing so as to clamp the same to the piston head.

The outer inner flanges 17 and 18 of the piston follower are either connected by a series of studs 12, as shown in Fig. 2, which may be cast integral with the flanges or they may be connected by a web 14, as shown in Fig. 5. In the ,first construction, the studs of course leave-large radial openings ll, 11, between the two flanges of the 'fol'lower and in the second construction smaller radial openings 13, 13, may be formed by boring or coring out, as shown in Fig. 5. 16 is the pressure headot theg'cylinder.

in operation the cup leather has its radial flange 3 firmly clamped between the piston head and follower with its upturned flange free to press against the cylinder walls. The expander ring 5 being loosely held behind. it and sprung inwardly so as to have its ends approximately adjacent, is free to expand by its elasticity and force the packing flange 4. smoothly and firmly againstthe' cylinder walls. Also when the compressed are seated. This cirair is admitted to the cylinder, it may pass 1 freely through the openings 13, 13, or 11, 11, according to which form of follower is employed and add its expansive force to the pressure holding the packing against the cylinder walls. The outer flange 18 of the piston fol-lower when made to closely fit the cylinder Walls, affords an additional hearing to support the weight of the piston when the cylinder is in a horizontal position and thereby reduces the wear upon the und'e-r side of the piston head 2 and relieves the packing from the necessity of supporting any of the piston head weight.

The advantages of my invention comprise the with which the improved form of expander ring may be made out of steel of any degree of temper (said ring being made 'of thin flat material, steel of any ordinary high temper can be stamped into the shape shown without dilficulty) the protection of the packing on both sides by piston head and follower so that dirt and gravel can not easily get tb it; the increase of the bearing surfaces of the piston as a viaole upon the cylinder walls, and the distribution of this bearing surface upon opposite sides of the packing; and the preservation of the full effectiveness of the air pressure itself in forcing the packing against the cylinder walls. Another advantage arising from the particular form of expander shown that it may have its upturned flange 6 of any width so as to fully cover even a very wide packing withoutintroducing any practical difliculties in the formation of said expander such would result in the effort to draw an expander of the type shown in my aforesaid patent with a wide upturned flange;

Having, therefore, described my invention, I claim:

1. The combination with a. piston head and a follower therefor of equal diameter, the parts being shaped to leave a circumferential recess between the piston and the fol lower, of a cup shaped flexible packing seated in said recess, one of the above named packing supporting elements being provided with openings to admit fluid pressure he hind the packing:

The combination with a piston head and a follower therefor of equal diameter, the parts being shaped to leave a circumfen ential recess between the piston and the follower, of a cup shaped flexible packing seated in said recess, one the above named packing supporting elements being provided with openings to admit fluid pressure-behind the packing and a discontinuous elastic packing expander ring also located in said recess behind the packing and free to e);- pand radially independently of the piston head and follower.

3., The combination with a piston-head and a follower therefor of equal diameter, the parts being shaped to leave a circumfer' ential recess between the piston and the follower, of a cup shaped flexible packing seated in said recess, one of the above named packiu supporting elements being provided with openings to admit fluid pressure behind the parking and a discontinuous elastic packing expander ring also located in said recess behind the packing said expander ring being formed 'of a flat strip of spring metal bent to an L-shaped cross section with abutting ends.

4, The combination with a piston head and follower of approximately equal diameters saaped to leave a circumferential recess between the two when assembled, of a'cup shaped flexible packing seated in said recess,

and an expander ring formed of a strip of elastic material of approximately even thickness throughout formed with an L' shaped cross section and bent into a circle with abutting ends, seated within said cup shaped packing.

5. The combination with a piston head and follower of approximately equal diameters shaped to leave a circumferential recess between the two when assembled, of a cup shaped flexible packing seated in said recess, and an expander ring formed of a strip of elastic material of approximately even thickness throughout formed with an L- shaped cross section and bent into a circle with abutting ends, seated within said cup shaped packing, the radially projecting flange of the packing being gripped between the piston head and follower when assembled, and the radially projecting flange of the oander ring also projecting between the piston head and follower, but the latter being provided with an annular recess in which the said expander flange is loosely seated CIIRISTENSON.

GEC \Vii'ncsses:

CHARLES E. Hoar-0N, (l. I. Bisiior. 

